[catcher22]

The light bulb just went off in my head...I have been troubleshooting a soft brake pedal for some time now. Given that the brake booster line is 'under boost', could old and broken vacuum lines attribute to a soft brake pedal? I'm planning to replace all of the vacuum lines very soon and am hoping it would resolve the soft brake pedal issue as well.

[Efthreeoh]

Lack of vacuum at the brake booster would cause a hard brake pedal. The brake booster is not under "boost". The brake booster is a just a big vacuum canister attached to the brake pedal that uses a vacuum/diaphragm mechanism to power-assist the brake pedal when you push on it. Leaking vacuum (from the vacuum line feeding the booster) reduces the amount of vacuum that is used to assist the effort (i.e. reduces the effort) to push the brake pedal, which is why the pedal gets harder to push.

You have either a brake system leak somewhere, air in the system somewhere, or a failing master cylinder.

[arkie6]

What do you mean by "under boost"? The brake booster is supplied by the vacuum pump. However, leaking vacuum lines could reduce vacuum supplied to the brake booster.

[catcher22]

Originally Posted by Efthreeoh

Lack of vacuum at the brake booster would cause a hard brake pedal. The brake booster is not under "boost". The brake booster is a just a big vacuum canister attached to the brake pedal that uses a vacuum/diaphragm mechanism to power-assist the brake pedal when you push on it. Leaking vacuum (from the vacuum line feeding the booster) reduces the amount of vacuum that is used to assist the effort (i.e. reduces the effort) to push the brake pedal, which is why the pedal gets harder to push.

You have either a brake system leak somewhere, air in the system somewhere, or a failing master cylinder.

Thanks. You're correct. I remember after I made this post that a long time ago I forgot to connect the hose when installing an intake and the brake pedal was rock hard. Freaked me out for a second. Oh well, the search continues...